Rice hull fiber environment-friendly material and preparation method thereof

Abstract

The invention discloses a rice hull fiber environment-friendly material and a preparation method thereof, and belongs to the technical field of polypropylene plastics. The preparation method is used for solving the technical problems that a plastic product prepared from polypropylene plastic in the prior art is difficult to degrade, and the mechanical property of the polypropylene plastic can be damaged by doping degradable organic components. The rice hull fiber environment-friendly material comprises rice hull fiber composite microspheres, a chlorinated polypropylene graft copolymer and related auxiliaries. The rice hull fiber composite microspheres are prepared by blending acylated rice hull fiber powder and a melt as a core material, wherein the melt is obtained by mixing rosin, silver nitrate and polylactic acid and heating; the chlorinated polypropylene grafted copolymer is obtained by taking chlorinated polypropylene as a main body and initiating grafting of methyl methacrylate and triallyl cyanurate. The rice hull fiber environment-friendly material prepared by the invention has the advantages of good mechanical property, bacteriostasis, flame retardance and degradability.

Description

Technical Field

[0001] The present invention relates to the technical field of polypropylene plastics, and specifically relates to a rice husk fiber environmental protection material and a preparation method thereof. Background Art

[0002] With the large-scale production and use of plastic products, plastic waste has been accumulating year by year. There are problems such as it being wantonly discarded and incompletely treated, causing it to migrate and transform in a multi-media environment, posing serious hazards to the environmental ecology and human health. Polypropylene is a currently widely used plastic, and polypropylene has the disadvantages of being difficult to degrade and severely damaging the ecological system. Rice husk fiber refers to substances such as cellulose and lignin left after peeling from rice husks; rice husk fiber is rich in cellulose, and its composition also contains more nutrients such as protein, minerals, and vitamins. Its production and use are very safe for the environment and the human body; rice husk fiber has natural degradability. If rice husk fiber is applied to the manufacture of polypropylene plastic products, it can accelerate degradation.

[0003] In the preparation of sanitary ware materials such as toilet lids, toilet tanks, and inner core components of water tanks, polypropylene plastics are often used. Among them, the isotactic structure of polypropylene has a high degree of stereoregularity and relatively high mechanical strength. However, polypropylene has the disadvantages of high brittleness and easy crystallization. In the early stage of preparing sanitary ware materials, polypropylene was often used as the carrier resin and heavy calcium carbonate as the filler to improve the mechanical properties of the prepared plastic; however, the above products are prone to caking under pressure and moisture absorption, and the products are prone to yellowing. After a period of use, the mechanical properties of such sanitary ware products will significantly decline. For example, patent application CN114773723A discloses a degradable polypropylene plastic and its preparation method and application. The polypropylene plastic includes polypropylene resin, a degradation agent, a filler, and related auxiliaries; the degradation agent is obtained by compounding PCL, PBTA, and PBA. However, the addition of the above compounded degradation agent will further damage the mechanical properties of the prepared plastic and is prone to yellowing and deterioration after a long time of use; in addition, if the above plastic is applied to sanitary ware, its antibacterial performance needs to be further enhanced.

[0004] In view of the technical defects in this regard, a solution is now proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a rice husk fiber environmental protection material and a preparation method thereof, which are used to solve the technical problem that in the prior art, polypropylene plastics are difficult to degrade, and doping degradable components will damage the mechanical properties of polypropylene plastics.

[0006] Technical problem.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] An environmentally friendly rice husk fiber material, comprising the following components by weight: 30-40 parts of rice husk fiber composite microspheres, 100 parts of chlorinated polypropylene graft copolymer, 0.1-0.5 part of antioxidant, 3-5 parts of stabilizer, and 1-2 parts of lubricant;

[0009] The rice husk fiber composite microspheres use acylated rice husk fiber powder and a melt blend as the core material, and the melt is obtained by mixing and heating rosin, silver nitrate, and polylactic acid;

[0010] The present invention uses a solution grafting method. In an organic solvent chloroform, using a free radical initiator, the chlorine atoms in chlorinated polypropylene can undergo a free radical reaction with the double bond in the monomer methyl methacrylate and the isocyanate group of triallyl cyanurate, and then a chlorinated polypropylene graft copolymer is formed.

[0011] The environmentally friendly rice husk fiber material prepared by the present invention is essentially a modified polypropylene-based plastic.

[0012] Furthermore, the preparation method of the chlorinated polypropylene graft copolymer includes the following steps:

[0013] A1. Ammonium persulfate is added to deionized water to obtain an initiator solution; chlorinated polypropylene is added to chloroform and stirred until the chlorinated polypropylene is completely dissolved to obtain a chlorinated polypropylene solution; the chlorinated polypropylene solution, methyl methacrylate, and triallyl cyanurate are mixed evenly to obtain a reactant;

[0014] A2. The reactant is heated to 80-90 °C for grafting reaction. During the reaction process, the initiator solution is added every two hours, and the initiator solution is added a total of three times. The grafting reaction lasts for 6-8 h to obtain a product;

[0015] A3. The product is added to ethanol, and the volume ratio of ethanol to the product is 1:10. The product forms a precipitate in ethanol; after post-treatment, the chlorinated polypropylene graft copolymer is prepared.

[0016] Using the solution grafting method, with chloroform as the organic solvent and ammonium persulfate as the initiator, under a certain high temperature condition, chlorinated polypropylene and methyl methacrylate, triallyl cyanurate undergo a free radical addition polymerization reaction to remove some of the chlorine atoms on the side chain of chlorinated polypropylene, and then a chlorinated polypropylene graft copolymer grafted with small molecules of methyl methacrylate and triallyl cyanurate is obtained.

[0017] Furthermore, in step A1, the dosage ratio of ammonium persulfate to deionized water is 3-5 g:50 mL; the dosage ratio of chlorinated polypropylene to chloroform is 5-10 g:100 g; the dosage ratio of the chlorinated polypropylene solution, methyl methacrylate, and triallyl cyanurate is 105-110 g:3-5 g:2.5-5 g.

[0018] Further, in step A2, the addition amounts of the three initiator solutions are equal, and the dosage ratio of the reactant to the total initiator solution is 110 - 120 g: 12 - 20 mL; in step A3, the volume ratio of ethanol to the product is 1:10; the post-process treatment steps include: filtering to remove the solvent in the precipitate and collecting the solid; washing the solid with deionized water and drying to prepare the chlorinated polypropylene graft copolymer; in step A4, the weight ratio of the chlorinated polypropylene graft copolymer to the styrene-butadiene-styrene block copolymer is 80 - 90:10 - 20, the melting and blending temperature is 150 - 160 °C, and the melting and blending duration is 5 - 10 min.

[0019] Further, the preparation method of the rice husk fiber composite microspheres includes the following steps:

[0020] B1. Rosin, silver nitrate, and polylactic acid are mixed in a mass ratio of 15 - 10:1 - 2:2 - 5 to obtain a melt; the melt and the acylated rice husk fiber powder are mixed evenly in a mass ratio of 1 - 2:3 - 5, and then heated to 160 - 180 °C to make the rosin and polylactic acid completely in a molten state, and mixed evenly to obtain the core material;

[0021] B2. The core material is added to the polyethylene glycol aqueous solution and homogenized under high pressure to obtain a dispersion system; the dispersion system is cooled to room temperature through a tubular heat exchanger to form a suspension; the suspension is spray-dried to prepare the rice husk fiber composite microspheres.

[0022] Under high-temperature conditions, rosin and polylactic acid are in a molten state; the melt is mixed with the acylated rice husk fiber powder and doped with a small amount of silver nitrate as the core material. Using the polyethylene glycol aqueous solution as the wall material, the above core material is coated by the spray-drying method to prepare the rice husk fiber composite microspheres.

[0023] Further, the preparation method of the acylated rice husk fiber powder includes the following steps: grinding the rice husk fiber to 200 - 300 meshes to obtain the rice husk fiber powder; mixing 100 mL of 3 - 5% wt NaOH solution and 20 - 30 mL of benzoyl chloride to obtain a reaction solution; immersing the rice husk fiber powder into the reaction solution according to a solid-liquid mass ratio of 1 - 3:10, reacting at 30 - 40 °C for 3 - 4 h, and then filtering to obtain a solid; washing with deionized water until the pH value is 7 to obtain the acylated rice husk powder.

[0024] The rice husk fiber powder can react with benzoyl chloride in the alkali solution to obtain the acylated rice husk powder.

[0025] Further, in step B2, the polyethylene glycol aqueous solution is prepared by the following steps: Mix 150 - 200 g of polyethylene glycol and 500 g of deionized water, and heat to 80 - 90°C to obtain the polyethylene glycol aqueous solution; the mass ratio of the core material to the polyethylene glycol aqueous solution is 4 - 5:1; the pressure of high-pressure homogenization is 25 - 30 MPa; during spray drying, the inlet air temperature is 195 - 200°C, and the outlet air temperature is 95 - 100°C.

[0026] As another aspect of the present invention, a preparation method of a rice husk fiber environmental protection material includes the following steps:

[0027] S1. High-speed mix rice husk fiber composite microspheres, chlorinated polypropylene graft copolymer, antioxidant, stabilizer and lubricant to obtain a mixture;

[0028] S2. Add the mixture into a twin-screw extruder for melt extrusion, and the melt extrusion temperature is 180 - 220°C. The obtained pellets are the prepared rice husk fiber environmental protection material.

[0029] Further, in step S1, the antioxidant is any one of antioxidant 1010, antioxidant 1076 or antioxidant 330; the stabilizer is lead stearate, and the lubricant is polyethylene wax; the rotation speed of high-speed mixing is 1500 - 2500 r / min, and the duration of high-speed mixing is 5 - 10 min.

[0030] The present invention has the following beneficial effects:

[0031] 1. Using polypropylene as the base material, the prepared engineering plastics can be used as sanitary wares such as toilet lids, toilet water tanks, and inner core parts of water tanks. In order to further improve the mechanical properties and chemical stability of the prepared plastics, the present invention uses chlorinated polypropylene to replace polypropylene to reduce the crystallinity of polypropylene-based plastics. However, chlorinated polypropylene has poor thermal stability. Under light or high-temperature conditions, the macromolecular chains will decompose and dechlorinate, and in severe cases, the molecular chains will break, thus affecting the stability of the prepared plastics. The present invention reacts chlorinated polypropylene with methyl methacrylate and triallyl cyanurate to remove some chlorine atoms on the side groups, which not only improves its own chemical stability but also enhances its own stiffness and flame retardancy. The chlorinated polypropylene graft copolymer also has high polarity and good compatibility with styrene-butadiene-styrene block copolymer.

[0032] 2. To improve the degradability of the environmentally friendly rice husk fiber material prepared, the present invention adds an appropriate amount of rice husk fiber composite microspheres to the raw materials. The rice husk fiber composite microspheres use a mixed melt of rosin, polylactic acid, silver nitrate, and acylated rice husk fiber powder as the core material, and polyethylene glycol as the wall material, and are synthesized by spray drying. Among them, rosin, polylactic acid, and rice husk fiber are all degradable, and the doped silver nitrate improves the antibacterial property of the prepared plastic products. The rice husk fiber powder can undergo an acylation reaction with benzoyl chloride in an alkaline solution to obtain acylated rice husk fiber, and the acylated rice husk fiber can improve its own mechanical properties and waterproofness. In addition, after the rice husk fiber powder is acylated, in the subsequent high-temperature co-melting state, it can undergo a chemical cross-linking reaction with rosin and polylactic acid to increase the cross-linking density of each component of the core material. In addition, preparing the rice straw fiber into a core-shell structure can improve the durability of the material. Using a chlorinated polypropylene graft copolymer as the base material, doping an appropriate amount of rice husk fiber composite microspheres and related additives, the prepared environmentally friendly rice husk fiber material has the advantages of good mechanical properties, antibacterial and flame retardant, and degradable. Detailed implementation manners

[0033] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the protection scope of the present invention.

[0034] In Examples 1-3 of the present invention, the chlorinated polypropylene used was purchased from Shanghai Huayi Chemical Auxiliary Co., Ltd., with the model A-1 and a chlorine content of 30-40% wt; the styrene-butadiene-styrene block copolymer used in Examples 1-3 of the present invention was purchased from Suzhou Linxi New Materials Co., Ltd., with the product number PA-757; the rice husk fiber used in Examples 4-6 of the present invention was purchased from Shenzhen Wansuyuan Rubber and Plastic Co., Ltd.; the rosin powder used in Examples 4-6 of the present invention was purchased from Wuhan Hongshan Xingya Trading Company, with the brand GXALKJ and the product number AL1017293056; the polyethylene glycol used in Examples 4-6 of the present invention was purchased from Zhengzhou Jiajie Chemical Products Co., Ltd., specifically polyethylene glycol PEG-400, with the product number 01, the model 400, and the density of 1.110 g / cm 3 ; the silver nitrate powder used in Examples 4-6 of the present invention was purchased from Xilong Science, with AR analytical purity and a content of ≥99.8% wt; the rosin used in Examples 4-6 of the present invention was purchased from Bozhou Tianyin Pavilion Pharmaceutical Co., Ltd., with the product number 01; the polylactic acid used in Examples 4-6 of the invention was purchased from Suzhou Jiangcangfa Plastic Co., Ltd., with the product number 9051-89-2 and the grade FY804.

[0035] Example 1

[0036] This embodiment provides a preparation method of a chlorinated polypropylene graft copolymer for rice husk fiber environmental protection materials, including the following steps:

[0037] A1. Add 3 g of ammonium persulfate to 50 mL of deionized water, stir and dissolve to obtain an initiator solution. By mass, add 5 g of chlorinated polypropylene to 100 g of chloroform, stir until the chlorinated polypropylene is completely dissolved to obtain a chlorinated polypropylene solution. Transfer 105 g of the chlorinated polypropylene solution to a 250 mL four-necked flask, then add 3 g of methyl methacrylate and 2.5 g of triallyl cyanurate, and mix evenly to obtain a reactant.

[0038] A2. Seal the four-necked flask, heat the 110 g of the reactant to 80 °C for grafting reaction; add the initiator solution once every two hours, add the initiator solution three times, and the amount added each time is the same. The total amount of the initiator used is 12 mL; the grafting reaction lasts for 6 h to obtain a product.

[0039] A3. Continuously and slowly add the product to ethanol, and the volume ratio of ethanol to the product is 1:10. The product forms a precipitate in ethanol; then filter to remove the solvent in the precipitate and collect the solid. The solid is washed with deionized water and dried to obtain a chlorinated polypropylene graft copolymer.

[0040] A4. By weight, add 80 parts of the chlorinated polypropylene graft copolymer and 10 parts of styrene-butadiene-styrene block copolymer to a twin-screw extruder for melt blending. The temperature of the melt blending is 150 °C, and the duration of the melt blending is 5 min to prepare a composite copolymer.

[0041] Example 2

[0042] This embodiment provides a preparation method of a chlorinated polypropylene graft copolymer for rice husk fiber environmental protection materials, including the following steps:

[0043] A1. Add 4 g of ammonium persulfate to 50 mL of deionized water, stir and dissolve to obtain an initiator solution. By mass, add 8 g of chlorinated polypropylene to 100 g of chloroform, stir until the chlorinated polypropylene is completely dissolved to obtain a chlorinated polypropylene solution. Transfer 108 g of the chlorinated polypropylene solution to a 250 mL four-necked flask, then add 4 g of methyl methacrylate and 3.5 g of triallyl cyanurate, and mix evenly to obtain a reactant.

[0044] A2. Seal the four-necked flask, heat 115 g of the reactants to 88 °C for grafting reaction; during the reaction, add the initiator solution every two hours, add it three times, with the same addition amount each time, and the total amount of initiator used is 15 mL; the grafting reaction lasts for 7 h to obtain the product.

[0045] A3. Continuously and slowly add the product to ethanol, with the volume ratio of ethanol to the product being 1:10, and the product forms a precipitate in ethanol; then filter to remove the solvent in the precipitate and collect the solid. The solid is washed with deionized water and dried to obtain the chlorinated polypropylene graft copolymer.

[0046] A4. By weight, add 85 parts of the chlorinated polypropylene graft copolymer and 15 parts of the styrene-butadiene-styrene block copolymer to a twin-screw extruder for melt blending. The melt blending temperature is 155 °C, and the melt blending duration is 7 min to prepare the chlorinated polypropylene graft copolymer.

[0047] Example 3

[0048] This example provides a preparation method of a chlorinated polypropylene graft copolymer for a rice husk fiber environmental protection material, including the following steps:

[0049] A1. Add 5 g of ammonium persulfate to 50 mL of deionized water, stir and dissolve to obtain the initiator solution. By mass, add 10 g of chlorinated polypropylene to 100 g of chloroform, stir until the chlorinated polypropylene is completely dissolved to obtain the chlorinated polypropylene solution. Transfer 110 g of the chlorinated polypropylene solution to a 250 mL four-necked flask, and then add 5 g of methyl methacrylate and 5 g of triallyl cyanurate, and mix evenly to obtain the reactants.

[0050] A2. Seal the four-necked flask, heat 120 g of the reactants to 90 °C for grafting reaction; add the initiator solution every two hours, add it three times, with the same addition amount each time, and the total amount of initiator used is 15 mL; the grafting reaction lasts for 8 h to obtain the product.

[0051] A3. Continuously and slowly add the product to ethanol, with the volume ratio of ethanol to the product being 1:10, and the product forms a precipitate in ethanol; then filter to remove the solvent in the precipitate and collect the solid. The solid is washed with deionized water and dried to obtain the chlorinated polypropylene graft copolymer.

[0052] A4. By weight, add 90 parts of the chlorinated polypropylene graft copolymer and 20 parts of the styrene-butadiene-styrene block copolymer to a twin-screw extruder for melt blending. The melt blending temperature is 160 °C, and the melt blending duration is 10 min to prepare the chlorinated polypropylene graft copolymer.

[0053] Example 4

[0054] This example provides a method for preparing rice husk fiber composite microspheres for rice husk fiber environmental protection materials, including the following steps:

[0055] B1. Grind the rice husk fiber to obtain rice husk fiber powder with a mesh size of 200. Mix 100 mL of 3% wt NaOH solution and 20 mL of benzoyl chloride to obtain a reaction solution. Immerse the rice husk fiber powder into the reaction solution according to a solid-liquid mass ratio of 1:10, react at 30 °C for 3 h with a stirring speed of 300 r / min, then filter to obtain a solid. Wash the solid with deionized water until the pH value is 7 to obtain acylated rice husk fiber powder.

[0056] B2. Mix rosin, silver nitrate and polylactic acid according to a mass ratio of 10:1:2 to obtain a melt; mix the melt and the acylated rice husk fiber powder according to a mass ratio of 1:3, then heat to 160 °C to make the rosin and polylactic acid completely in a molten state, and mix well to obtain the core material.

[0057] B3. Mix 150 g of polyethylene glycol and 500 g of deionized water, heat to 80 °C to obtain an aqueous polyethylene glycol solution. Add the core material to the aqueous polyethylene glycol solution and homogenize it with a high-pressure homogenizer. The mass ratio of the aqueous polyethylene glycol solution to the core material is 4:1, and the pressure of high-pressure homogenization is 25 MPa to obtain a dispersion system; cool the dispersion system to room temperature through a tubular heat exchanger to form a suspension, and spray-dry the suspension with a pneumatic spray drying device. The inlet air temperature is 195 °C and the outlet air temperature is 95 °C to prepare rice husk fiber composite microspheres.

[0058] Example 5

[0059] This example provides a method for preparing rice husk fiber composite microspheres for rice husk fiber environmental protection materials, including the following steps:

[0060] B1. Grind the rice husk fiber to obtain rice husk fiber powder with a mesh size of 220. Mix 100 mL of 4% wt NaOH solution and 25 mL of benzoyl chloride to obtain a reaction solution. Immerse the rice husk fiber powder into the reaction solution according to a solid-liquid mass ratio of 2:10, react at 35 °C for 3.3 h with a stirring speed of 400 r / min, then filter to obtain a solid. Wash the solid with deionized water until the pH value is 7 to obtain acylated rice husk fiber powder.

[0061] B2. Mix rosin, silver nitrate and polylactic acid according to a mass ratio of 12:1:3 to obtain a melt; mix the melt and the acylated rice husk fiber powder according to a mass ratio of 2:4, then heat to 170 °C to make the rosin and polylactic acid completely in a molten state, and mix well to obtain the core material.

[0062] B3. Mix 170 g of polyethylene glycol and 500 g of deionized water, heat to 85 °C to obtain an aqueous polyethylene glycol solution. Add the core material to the aqueous polyethylene glycol solution and homogenize it using a high-pressure homogenizer. The mass ratio of the aqueous solution to the core material is 4:1, and the pressure of high-pressure homogenization is 28 MPa to obtain a dispersion system; the dispersion system is cooled to room temperature through a tubular heat exchanger to form a suspension, and the suspension is spray-dried using a pneumatic spray drying device. The inlet air temperature is 197 °C and the outlet air temperature is 97 °C to prepare rice husk fiber composite microspheres.

[0063] Example 6

[0064] This example provides a preparation method of rice husk fiber composite microspheres for rice husk fiber environmental protection materials, including the following steps:

[0065] B1. Grind rice husk fibers to obtain rice husk fiber powder with a mesh size of 300. Mix 100 mL of 5% wt NaOH solution and 30 mL of benzoyl chloride to obtain a reaction solution. Immerse the rice husk fiber powder into the reaction solution according to a solid-liquid mass ratio of 3:10, react at 40 °C for 4 h, with a stirring speed of 500 r / min, then filter to obtain a solid. Wash the solid with deionized water until the pH value is 7 to obtain acylated rice husk fiber powder.

[0066] B2. Mix rosin, silver nitrate, and polylactic acid according to a mass ratio of 15:2:5 to obtain a melt; mix the melt and the acylated rice husk fiber powder according to a mass ratio of 2:5, then heat to 180 °C to make the rosin and polylactic acid completely in a molten state and mix well to obtain the core material.

[0067] B3. Mix 200 g of polyethylene glycol and 500 g of deionized water, heat to 90 °C to obtain an aqueous polyethylene glycol solution. Add the core material to the aqueous polyethylene glycol solution and homogenize it using a high-pressure homogenizer. The mass ratio of the aqueous solution to the core material is 5:1, and the pressure of high-pressure homogenization is 30 MPa to obtain a dispersion system; the dispersion system is cooled to room temperature through a tubular heat exchanger to form a suspension, and the suspension is spray-dried using a pneumatic spray drying device. The inlet air temperature is 200 °C and the outlet air temperature is 100 °C to prepare rice husk fiber composite microspheres.

[0068] Example 7

[0069] This example provides a preparation method of rice husk fiber environmental protection materials, including the following steps:

[0070] S1. By weight, add 30 parts of the rice husk fiber composite microspheres prepared in Example 4, 100 parts of the chlorinated polypropylene graft copolymer prepared in Example 1, 0.1 part of antioxidant 1010, 3 parts of stabilizer lead stearate, and 1 part of lubricant polyethylene wax to a high-speed mixer, mix at 1500 r / min for 5 min to obtain a mixture.

[0071] S2. The mixture is added to a twin-screw extruder for melt extrusion at a temperature of 180 °C, and the obtained pellets are the rice husk fiber environmental protection material.

[0072] Example 8

[0073] This example provides a method for preparing a rice husk fiber environmental protection material, including the following steps:

[0074] S1. By weight, 33 parts of the rice husk fiber composite microspheres prepared in Example 5, 100 parts of the chlorinated polypropylene graft copolymer prepared in Example 2, 0.3 part of antioxidant 1076, 4 parts of stabilizer lead stearate, and 1 part of lubricant polyethylene wax are added to a high-speed mixer and mixed at 2000 r / min for 8 min to obtain a mixture.

[0075] S2. The mixture is added to a twin-screw extruder for melt extrusion at a temperature of 200 °C, and the obtained pellets are the rice husk fiber environmental protection material.

[0076] Example 9

[0077] This example provides a method for preparing a rice husk fiber environmental protection material, including the following steps:

[0078] S1. By weight, 40 parts of the rice husk fiber composite microspheres prepared in Example 6, 100 parts of the chlorinated polypropylene graft copolymer prepared in Example 3, 0.5 part of antioxidant 330, 5 parts of stabilizer lead stearate, and 2 parts of lubricant polyethylene wax are added to a high-speed mixer and mixed at 2500 r / min for 10 min to obtain a mixture.

[0079] S2. The mixture is added to a twin-screw extruder for melt extrusion at a temperature of 220 °C, and the obtained pellets are the rice husk fiber environmental protection material.

[0080] Comparative Example 1

[0081] The difference between this comparative example and Example 9 is that when preparing the chlorinated polypropylene graft copolymer, only 10 g of methyl methacrylate is added to obtain the reactant.

[0082] Comparative Example 2

[0083] The difference between this comparative example and Example 9 is that when preparing the chlorinated polypropylene graft copolymer, only 10 g of triallyl cyanurate is added to obtain the reactant.

[0084] Comparative Example 3

[0085] The difference between this comparative example and Example 9 is that when preparing the rice husk fiber composite microspheres, the rice husk fibers are not acylated.

[0086] Comparative Example 4

[0087] The difference between this comparative example and Example 9 is that rosin, silver nitrate, polylactic acid, and acylated rice husk fiber powder are mixed evenly according to a mass ratio of 10:1:2:39 to replace the same mass of rice husk fiber composite microspheres.

[0088] Performance test:

[0089] 1. Use a rotational rheometer to detect the viscosity and modulus of the chlorinated polypropylene graft copolymer prepared in Examples 1-3 and Comparative Examples 1-2; the test temperature is 230 °C, the strain amplitude is 2%, and the frequency is 0.1 - 100 rad / s.

[0090] 2. Sequentially prepare the chlorinated polypropylene graft copolymer prepared in Examples 1-3 and Comparative Examples 1-2 into standard rectangular specimens with specifications of 8 mm × 10 mm × 4 mm; use a fully automatic notch cutting machine to notch the impact specimens at an angle of 45° and a depth of 2 mm. The impact performance test is carried out using a pendulum impact testing machine and tested according to the standard of GB / T 1843-2008.

[0091] 3. Use an injection molding machine to prepare the chlorinated polypropylene graft copolymer prepared in Examples 1-3 and Comparative Examples 1-2 into standard rectangular specimens with specifications of 80 mm × 10 mm × 4 mm, and conduct a flexural property test according to GB / T 9341-2008 "Determination of Flexural Properties of Plastics", with a test speed of 2 mm / min and a deflection of 6 mm.

[0092] 4. Use an injection molding machine to prepare the chlorinated polypropylene graft copolymer prepared in Examples 1-3 and Comparative Examples 1-2 into standard dumbbell-shaped specimens with specifications of 170 mm × 10 mm × 4 mm, and conduct a tensile property determination according to GB / T 1040.1-2006 "Determination of Tensile Properties of Plastics", where the tensile speed is 50 mm / min.

[0093] Table 1. Test data of sample properties

[0094]

[0095] Data analysis: Analyze the data in Table 1. The chlorinated polypropylene graft copolymers prepared in Examples 1-3 of the present invention all have relatively high viscosity values. However, in Comparative Example 2, compared with the chlorinated polypropylene graft copolymer, the viscosity value of the chlorinated polypropylene graft copolymer prepared by adding the same mass of triallyl cyanurate is significantly reduced.

[0096] The chlorinated polypropylene graft copolymers prepared in Examples 1-3 of the present invention have relatively high impact strength values; however, in Comparative Example 1, compared with the chlorinated polypropylene graft copolymer, the impact strength value of the chlorinated polypropylene graft copolymer prepared by adding the same mass of methyl methacrylate is significantly reduced.

[0097] The chlorinated polypropylene graft copolymers prepared in Examples 1-3 of the present invention all have good mechanical properties, manifested as relatively high flexural strength values and tensile strength values for the prepared chlorinated polypropylene graft copolymers; the flexural strength values and tensile strength values of the products prepared in Comparative Example 1 and Comparative Example 2 are relatively low.

[0098] 4. The antibacterial properties of the rice husk fiber environmental protection materials prepared in Examples 7-9 and Comparative Examples 3-4 were detected. The antibacterial circle method was used to measure the diameter of their antibacterial circles.

[0099] 5. The flame retardant properties of the rice husk fiber environmental protection materials prepared in Examples 7-9 and Comparative Examples 3-4 were determined, and their limiting oxygen index values were detected.

[0100] Table II. Test data of sample properties

[0101]

[0102] Data analysis: The rice husk fiber environmental protection materials prepared in Examples 7-9 and Comparative Examples 3-4 of the present invention all have excellent antibacterial properties, manifested as relatively high direct antibacterial circle values; it shows that as long as an appropriate amount of silver nitrate powder is added to the prepared rice husk fiber environmental protection materials, the prepared rice husk fiber environmental protection materials can have excellent antibacterial properties.

[0103] The rice husk fiber environmental protection materials prepared in Examples 7-9 and Comparative Examples 3-4 of the present invention all have excellent flame retardant properties; however, in Comparative Example 4, when preparing the rice husk fiber environmental protection materials, they were not prepared into rice husk fiber composite microspheres, and the composite microspheres with a core-shell structure have better flame retardant properties, so the limiting oxygen index value of the material prepared in Comparative Example 4 is the lowest.

[0104] The above content is only an example and explanation of the structure of the present invention. Those skilled in the art of the present technology make various modifications or supplements to the described specific embodiments or use similar methods for substitution. As long as they do not deviate from the structure of the invention or exceed the scope defined by this claims, they should all fall within the protection scope of the present invention.

[0105] In the description of this specification, the description referring to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0106] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the present invention to only the specific implementation manners. Obviously, according to the content of this specification, many modifications and changes can be made. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. An environmentally friendly rice husk fiber material, characterized in that, It includes the following components by weight: 30 - 40 parts of rice husk fiber composite microspheres, 100 parts of chlorinated polypropylene graft copolymer, 0.1 - 0.5 part of antioxidant, 3 - 5 parts of stabilizer, and 1 - 2 parts of lubricant; The rice husk fiber composite microspheres use acylated rice husk fiber powder and a melt blend as the core material, and the melt is obtained by mixing and heating rosin, silver nitrate, and polylactic acid; The chlorinated polypropylene graft copolymer is based on chlorinated polypropylene and is obtained by initiating the grafting of methyl methacrylate and triallyl cyanurate.

2. The environmentally friendly rice husk fiber material according to claim 1, wherein, The preparation method of the chlorinated polypropylene graft copolymer includes the following steps: A1. Ammonium persulfate is added to deionized water to obtain an initiator solution; chlorinated polypropylene is added to chloroform and stirred until the chlorinated polypropylene is completely dissolved to obtain a chlorinated polypropylene solution; the chlorinated polypropylene solution, methyl methacrylate, and triallyl cyanurate are mixed evenly to obtain a reactant; A2. The reactant is heated to 80 - 90 °C for grafting reaction. During the reaction process, the initiator solution is added once every two hours, and the initiator solution is added a total of three times. The grafting reaction lasts for 6 - 8 h to obtain a product; A3. The product is added to ethanol, and the volume ratio of ethanol to the product is 10:

1. The product forms a precipitate in ethanol; after post - process treatment, the chlorinated polypropylene graft copolymer is prepared; A4. The chlorinated polypropylene graft copolymer and styrene - butadiene - styrene block copolymer are added to a twin - screw extruder for melt blending to obtain a composite.

3. The environmentally friendly rice husk fiber material according to claim 2, characterized in that, In step A1, the dosage ratio of ammonium persulfate to deionized water is 3 - 5 g:50 mL; the dosage ratio of chlorinated polypropylene to chloroform is 5 - 10 g:100 g; the dosage ratio of the chlorinated polypropylene solution, methyl methacrylate, and triallyl cyanurate is 105 - 110 g:3 - 5 g:2.5 - 5 g.

4. The environmentally friendly rice husk fiber material according to claim 2, characterized in that, In step A2, the addition amounts of the three initiator solutions are equal, and the dosage ratio of the reactant to the total initiator solution is 110 - 120 g:12 - 20 mL; The post - process treatment steps include: filtration, precipitation, and solvent separation to collect the solid; the solid is washed with deionized water and dried to obtain the chlorinated polypropylene graft copolymer; in step A4, the weight ratio of the chlorinated polypropylene graft copolymer to the styrene - butadiene - styrene block copolymer is 80 - 90:10 - 20, the melt blending temperature is 150 - 160 °C, and the melt blending duration is 5 - 10 min.

5. The environmentally friendly rice husk fiber material according to claim 1, characterized in that, The preparation method of the rice husk fiber composite microspheres is characterized by including the following steps: B1. Rosin, silver nitrate, and polylactic acid are mixed in a mass ratio of 15 - 10:1 - 2:2 - 5 to obtain a melt; the melt and acylated rice husk fiber powder are mixed evenly in a mass ratio of 1 - 2:3 - 5, and then heated to 160 - 180 °C to make the rosin and polylactic acid completely in a molten state, and then mixed evenly to obtain the core material; B2. The core material is added to an aqueous polyethylene glycol solution and homogenized under high pressure to obtain a dispersion system; the dispersion system is cooled to room temperature through a tubular heat exchanger to form a suspension; the suspension is spray - dried to prepare the rice husk fiber composite microspheres.

6. The environmentally friendly rice husk fiber material according to claim 5, wherein In step B1, the preparation method of the acylated rice husk fiber powder includes the following steps: grinding the rice husk fiber to 200-300 meshes to obtain rice husk fiber powder; mixing 3-5%wt of NaOH solution and benzoyl chloride to obtain a reaction solution; the dosage ratio of the NaOH solution to benzoyl chloride is 100mL:20-30mL; immersing the rice husk fiber powder into the reaction solution according to the solid-liquid mass ratio of 1-3:10, reacting at 30-40°C for 3-4h, then filtering to obtain a solid; washing with deionized water until the pH value is 7 to obtain the acylated rice husk powder.

7. The environmentally friendly rice husk fiber material according to claim 5, characterized in that, In step B2, the polyethylene glycol aqueous solution is prepared by the following steps: mixing polyethylene glycol and deionized water, heating to 80-90°C to obtain the polyethylene glycol aqueous solution; wherein, the dosage ratio of polyethylene glycol to deionized water is 150-200g:500g; the mass ratio of the core material to the polyethylene glycol aqueous solution is 4-5:1; the pressure of high-pressure homogenization is 25-30MPa; during spray drying, the inlet air temperature is 195-200°C, and the outlet air temperature is 95-100°C.

8. A preparation method of the rice husk fiber environmental protection material according to any one of claims 1-7, characterized in that, It includes the following steps: S1. High-speed mixing the rice husk fiber composite microspheres, chlorinated polypropylene graft copolymer, antioxidant, stabilizer and lubricant to obtain a mixture; S2. Adding the mixture into a twin-screw extruder for melt extrusion, and the melt extrusion temperature is 180-220°C, and the obtained pellets are the prepared rice husk fiber environmental protection material.

9. The preparation method of a rice husk fiber environmental protection material according to claim 8, characterized in that, In step S1, the rotation speed of high-speed mixing is 1500-2500r / min, and the duration of high-speed mixing is 5-10min.

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